Maybe some involved more closely with the BCV/BWV dues & transportation issue a few years ago can chime in but IIRC, the costs are divided up more by potential usage than actual usage. And also IIRC, it's by density (# of people per room) rather than per room in such a way that DVC tends to pay more than the resort of the resort(s). But as noted, it's all covered by the owners at Riviera only for the DVC portion.
Back in 2004, there was a likely mistake in the transportation budget discovered by a couple of DVC owners. The DVC owners took action and wrote detailed letters to DVCMC stating their analysis of the transportation costs and asked DVCMC to please review the accounting costs and provide an explanation for the possible discrepancy.
DVCMC responded to the requests and the DVCMC Finance Manager explained that the Epcot Resorts transportation costs were being allocated initially using a fixed cost split and then secondly with a variable cost split:
1) Split the total Epcot Resorts transportation costs by 33/33/33 for each resort group: Swan & Dolphin / Boardwalk Villas & Boardwalk Inn / Yacht Club & Beach Club & Beach Club Villas.
2) For each Disney resort group, the costs were then split based upon guest usage (occupancy).
BCV 19% / YC & BC 81%
BWV 58% / BWI 42%.
After being challenged to validate the transportation costs, the DVCMC Finance Manager discovered that the boat costs were not being allocated properly for BCV. This was corrected in the 2005 budget.
There was also a discussion about the "fairness" of doing the 1/3 split first between the resort groups before allocating the costs based upon guest usage (occupancy). The DVCMC Finance Manager stated that it was the practice that they had chosen to use. (Part of the difficulty of sharing the transportation costs entirely based upon usage (occupancy)
may have stemmed from the Swan & Dolphin not wanting to share occupancy data with DVCMC, and this
may be why they did the 1/3 resort group split first.)
Based upon the accounting practice at the time, the definition of a "transportation stop" was a resort group: (1) Swan & Dolphin; (2) BWV & BWI; (3) YC & BC & BCV and it was not the actual number of "stops" that a bus made at a pickup/dropoff station. In 2004 there were 2 stops at Swan & Dolphin, 2 at YC & BC & BCV, and 1 at BWV & BWI.
Initially, the DVCMC Finance Manager was skeptical of the request and very confident of their accounting practices. He was embarrassed to discover the accounting error. Overall, DVCMC was open and responsive to the requests by the DVC owners and corrective action was taken to resolve the accounting mistake. The question of "fairness" was not answered.
DVCMC provides management services for the DVC owners. If you are an owner at Riviera and want to know how the transportation costs were estimated for a new transportation service at the resort, send an email.